In a lab in Brazil, a rat faced an opening in the wall of its enclosure, and two levers. If it detected with its whiskers that the opening was narrow, it was supposed to press one lever. If the opening was wide, it was supposed to press the other. Choose the right lever, and it would be rewarded with a sip of water.

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With practice, the rat learned to press the correct lever 95 percent of the time. Then came the remarkable part.

Researchers implanted one set of electrodes in the brain of the rat in Brazil, and another set of electrodes in the brain of a second rat at Duke University. Via an Internet connection, they set it up so that a signal from the brain of the rat in Brazil would be sent, in simplified form, directly to the brain of the rat in North Carolina. The rat in North Carolina also faced two levers, but had no information to go on as to which one to press—except for the signal coming from the first rat's brain.

The test: Could the rat in North Carolina press the correct lever, based on the width of the opening in the enclosure of the rat in Brazil? Six or seven times out of 10, it did.

The study, published Thursday morning in the open-access journal Scientific Reports, appears to be the first to allow animals to communicate via a brain-to-brain computer interface. The researchers, led by neuroscientist Miguel Nicolelis at Duke, say the feedback actually went both ways: When the second rat chose the correct lever, the first rat got an additional reward, which apparently encouraged it to send a clearer and stronger brain signal the next time. If that's true, it would amount to not only communication, but a form of cooperation.

Nicolelis believes this opens the possibility of building an "organic computer" that links the brains of multiple animals into a single central nervous system, which he calls a "brain-net." Are you a little creeped out yet? In a statement, Nicolelis adds:

We cannot even predict what kinds of emergent properties would appear when animals begin interacting as part of a brain-net. In theory, you could imagine that a combination of brains could provide solutions that individual brains cannot achieve by themselves.

That sounds far-fetched. But Nicolelis' lab is developing quite the track record of "taking science fiction and turning it into science," says Ron Frostig, a neurobiologist at UC-Irvine who was not involved in the rat study. "He's the most imaginative neuroscientist right now." (Frostig made it clear he meant this as a complement, though skeptics might interpret the word less charitably.)

The potential applications of brain-to-brain interfaces for humans aren't entirely clear. Few people today are eager to have electrodes implanted in their brains. And the brain signals that the rats transmitted were relatively simplistic, so there's no guarantee that the technology would ever work for the transmission of anything as complex as abstract thoughts or memories.

Still, Frostig says the rat study creates exciting possibilities for future research. "We can't yet say how this will help people. But this is the first time that it's been proven that something like this can be done at all. I think it's wonderful."